Integrated Text and Image Understanding for Document Understanding

Integrated Text and Image Understanding for Document Understanding Sttzalzo, e Liebowitz T~tylor, Deborah A. Dahl, Mark Lips/~utz, Carl Weir, Lewis M. Norton, Roslyn Nilson and Marcia Liueb~trgcr Unisys Corporation Paoli, PA 19301 ABSTRACT Because of the complexity of documents and the variety of ap- plications which must be supported, document understand- ing requires the integration of image understanding with text understanding. Our docum(,nt understanding technology is implemented in a system called IDUS (Intelligent Document Undcrstanding System), which creates the data for a text retrieval application and the automatic generation of hyper- ttrxt li.ks. This paper summarizes the areas of research dur- ing IDUS development where we have found the most benelit from the integration of image and text understanding. 1. INTRODUCTION As more and more of our daily transactions involve comput- ers, we would expect the volume of paper documents gener- ated to decrease. However, exactly the opposite is happening. ('onsiderable amounts of information are still generated only in paper form. This, compounded by volumes of legacy l)a.per documents still cluttering offices, creates a need for efficient methods for converting hardcopy material into a computer- usable form. However, because of the Sol)histication of ap- plications requiring electronic documents (e.g. routing and retrieval) and the complexity of the documents themselves, it is not sufficient to simply scan and perform OCR (optical character recognition) on documents; deeper understanding of the document is needed. Comprehensive document understanding involves determin- ing the form (layout), as well as the function and the meaning of the document. Document understanding is thus a technol- ogy area which benefits greatly from the integration of text understanding with image understanding. Text understand- ing is necessary to operate on the textual content of the docu- ment and image understanding is necessary to operate on the pixel content of the document. We have found great benefit from intertwining the two technologies instead of employing them in a pipeline fashion. We expect that more sophisti- cated document applications in the future will require even closer knitting. Our document understanding technology is implemented in a system called IDUS (Intelligent Document Understanding System, described in Section 2), which creates the data for a text retrieval application and the automatic generation of hypertext links. This paper summarizes areas of research during IDUS development where we have found the most benefit from the integration of image processing with natural language/text processing: Document layout analysis (Section 3), OCR correction (Section 4), and Text analysis (Section 4). We also discuss two applications we have implemented (Sections 5 and 6) and future plans in Section 7. 2. GENERAL IDUS SYSTEM DESCRIPTION IDUS employs four general technologies - image understand- ing, OCR, do(:ument layout analysis and text understand- ing - in a knowledge-based cooperative fashion[l~ 2]. The curre,t implemenlation is on a SPAl~Cstation TM II with the UNIX TM operating system using the 'C' and Prolog programlning languages. OCR is performed with the Xe- rox hnaging Systems ScanWorX TM Application Program- mer's Interface toolkit. All features are accessible via an …

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